Grant to help study of iron, copper in ocean water

ORONO, Maine — Two University of Maine scientists and a colleague from Colby College in Waterville recently received a $1.3 million grant for their work on technology that measures iron and copper in ocean water and could have implications for climate change research.

The four-year National Science Foundation grant allows professors Mark Wells and Carl Tripp of UMaine and Whitney King of Colby to develop a small sensor which can be attached to a mooring, a drifting float or to underwater gliders. The third option is ideal, Wells said, because gliders are controlled remotely and their data-gathering sensors can run 24 hours a day, seven days a week.

Wells, Tripp, King, UMaine doctoral graduate Cuihong Jung and doctoral candidate Eric Roy have spent the past three years developing a nanostructured surface technology that binds iron from seawater. The grant will help refine the surface so it can be incorporated into a prototype sensing device for use on ocean-observing platforms.

The sensor is actually a 1- centimeter-by-1-centimeter film of an organic molecule that is made from bacteria. The film binds with iron from seawater and allows scientists to analyze iron levels. Copper levels also can be measured, although not to the extent of iron.

“It’s a film we can put on different [surfaces],” said Wells, a professor of oceanography in the school of marine sciences. “That is something which has eluded many people for a long time. It’s a major jump forward in trying to analyze things found in ocean waters.”

Wells said the sensors eventually could be used on something such as the Gulf of Maine Ocean Observing System, known as GoMOOS, a buoy system that has a partnership with UMaine. Eventually, the data gathered from the sensors could be sent back to researchers by cellular or satellite technology.

The process now used to measure iron and copper requires that samples be collected individually from large research vessels and analyzed in a laboratory.

Iron and copper are metals important for sustaining the natural growth of phytoplankton, the tiny oceanic plants that serve as the foundation of marine ecosystems.

Phytoplankton also sequester carbon dioxide, the predominant greenhouse gas responsible for global warming. Scientists who model climate change examine phytoplankton levels in the ocean because they’ve found that the more phytoplankton, the lower the levels of carbon dioxide. Low levels of iron would indicate low levels of phytoplankton.

“There is some indication that copper might be involved but there is really no question now that iron is involved,” Wells said. “Climate change scientists need a lot more data about iron concentration in the ocean and how that iron changes over time.”

There are plenty of ways to take measurements of, say, temperature and salinity, and there are relatively easier ways to measure levels of nutrients in water. The challenge in measuring iron is in its extremely low levels.

“That’s a big challenge because iron in the open ocean is at very, very low levels,” Wells said. “To put it in perspective, we must measure a drop of food coloring added to an Olympic-size pool. The difference between a drop and half a drop could have major consequences for how much carbon dioxide phytoplankton can sequester.”

The researchers tested the film over the past few years in the Gulf of Alaska, which is known to have particularly low iron levels. The results mimicked the numbers found in already accepted testing methods, Wells said.

The next step for the group is developing a different type of surface on which to place the film in order to maximize the water flow by the sensor. The researchers also are hoping to miniaturize the whole system, which is now the size of a steamer trunk, to the size of a shoebox or even a cell phone.

“Certainly [the grant will help] make a lot of progress toward it,” Wells said. “There’s every reason to be optimistic.”